1. Field of the Invention
The present invention relates to a luminescent character display device and, more particularly, to a fluorescent character display device having a plurality of anodes disposed in a matrix form and each coated with a fluorescent layer thereon and adapted to display multi-digit characters, symbols, graphic patterns, etc. by selectively actuating the above-mentioned anodes.
2. Description of the Prior Art
A multi-digit fluorescent display tube now widely used has a pattern display section composed of a plurality of sub-sections for the respective digits, each sub-section being formed, for instance, of seven segment anodes disposed in the form of the letter "8" and each coated with a fluorescent layer, and produces the display of each digit by selectively actuating three segment anodes.
This segment-type display device has advantage in that it can display ten figures from 1 to 9 for each digit using a small number of segment anodes; however, it is difficult for the device to display various characters except these figures.
Under these circumstances, a fluorescent display tube is being put into practical use, which has a sub-section for each digit of the pattern display section composed of eight segment anodes disposed in a lattice form or of sixteen segment anodes disposed in a lattice form with diagonals and which actuates these segment anodes thereby performing fluorescent character display.
However, the characters displayed by these segment-type devices are inevitably become unnatural in shape and therefore are illegible. In addition, the characters that can be displayed by these segment-type devices are limited to, for instance, figures and a part of alphabetical characters; thus it is difficult for these devices to display various characters, symbols, graphic patterns etc. at will.
In order to eliminate these disadvantages of the conventional segment-type display devices, there has been proposed a dot-type display device which has a pattern display section composed of a plurality of sub-sections for the respective digits, each sub-section for digit being formed of a plurality of dot-shaped anodes disposed in a matrix form and each coated with a fluorescent layer, and which performs luminescent character display by selectively actuating these anodes.
However, this dot-matrix type fluorescent display tube requires a great number of dot-shaped anodes with fluorescent layers and connecting wires thereof, which are accompanied by difficulties in production. In addition, it requires a great number of drive circuits for selectively actuating the above-mentioned dot-shaped anodes with the result that it becomes complicated in construction and therefore high in cost.